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How Much Alcohol Really Gets Into Breastmilk?

Recently, I got a comment on one of my older posts on drinking and breastfeeding. The post was specifically about drinking Guinness and about whether or not the rumor that Guinness helped to make more milk was true. In the post, I also talk about other affects of drinking alcohol while nursing, specifically sleep. The commenter seemed agitated (although I could be misreading) when she said:

You shouldn’t drink ANY alcohol while you’re nursing. Everything you put into your body is consumed by your baby. They even taste it. If you wouldn’t feed it, then don’t eat it.

Hmmm. I’ve now nursed a combined 26 months (and counting) and as long as I’ve been nursing, I’ve had one beer OR one glass of wine most nights. The day has been long. Both my babies are in bed. It’s my time, and I’d like to relax. I’ve been told by my doctor that 1-2 drinks a night is not a problem when it comes to nursing but I decided to look into more information on the subject.
La Leche League has a whole page devoted to this topic with lots of interesting information, which I encourage you to check out. There seems to be a general consensus that yes, alcohol does get into your breast milk, although most of their sources say it’s not harmful.

Regardless, my husband, T, being the science Ph.D. snob that he is, does not trust one iota of information on LLL’s page as factually scientific. So, we (he) decided to do a little math computation to figure out exactly how much alcohol was really getting into the blood stream and thus the milk. See his results below:

Alcohol appears in mother’s milk at about the same concentration that alcohol is in the mother’s blood (one informal but convincingly scientific post found it to be much less). So, one drink (consumed quickly) will typically give us a Blood Alcohol Level (BAC) of 0.03%. This means that there is 0.03grams of alcohol in each 100mL of our blood. So, if your baby has about 4-5 ounces of milk (100mL), he/she will ingest about 0.03grams of alcohol.

For comparison, a standard drink (one beer, a glass of wine) has about 14 grams of alcohol in it. So, the baby is drinking the equivalent of 1/175th of a beer. This is like having a beer the size of a marble. Babies typically weigh about 1/10th of an adult (17lb baby, 170lb adult), so the effect on their system will be magnified. Very young infants metabolize alcohol at about half the rate of an adult, but soon the rates are similar to adults.

So, your baby’s BAC will be about 5% of yours. This seems like an insignificant amount, but there may be be some developmental impact on babies that don’t apply to adults. One major example of this is low weight gain. If my baby had weight gain issues (and I was a female who breastfed), I would eliminate alcohol just to take it out of the list of possible causes.

One last and important point: everything above assumed that you fed your baby right after slamming the beer. If you have one beer and wait a few hours to feed, your BAC and the risk to your baby are basically zero. Instead, feed baby, have a beer, wait a few hours, feed baby again. Check out this useful graph. Also note that having many beers is much worse than having one beer, since the window of peak BAC is much wider.

So, there you have it. Look, even with this math and science and all the information available about breastfeeding and alcohol, we all have to make our own choices. We’ve made ours.

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Content provided on this site is for entertainment or informational purposes only and should not be construed as medical or health, safety, legal or financial advice. Click here for additional information.